LETHAL CONTROL
The ethics behind lethal control on invasive species is riddled with opinion. In the United States, the feral cat population is more of a nuisance, besides the potential to spread disease. However on several islar environments, feral cats can be attributed to the extinction or threatening of many native species. Unfortunately, lethal control is the only way to ensure that the feral cat population is handled so that native species can survive1.
Poison
- Unfortunately, poison baiting is used to decrease feral cat populations in several countries. Although difficult to administer, poisoning is the cheapest of all approaches to invasive species control2.
- Prey items for feral cats are typically baited with poison. This can lead to issues however, as other mammalian species have access to the poisoned bait. A study in Australia showed that 5.8% of vertebrate species, carnivorous marsupials, and ground birds have consumed poison bait set out for feral cats. Worse yet, it was discovered that the threatened Tasmanian devil (Sarcophilus harrisil) and several species of threatened birds all had access to poisoned baits as well3.
- Poison baiting is further complicated by the fact that most cats hunt and prefer eating live prey. Making a baited prey item enticing for a cat can be difficult1.
Shooting
- In New Zealand, the most widely used method for eradicating feral cats is by shooting. Shooting is a time and labor-intensive method of feral cat population control2 (Doherty & Algar, 2015). The humaneness and effectiveness of the shot is solely dependent on the skill of the shooter, and is not the ideal solution to the feral cat problem4.
- Shooting is most effective when performed at night using night vision, and ensuring adequate caliber and accuracy is essential to this approach1.
- This approach has shown to be effective only in small, controlled populations of feral cats with continual applications1.
- Shooting could be the only way to eradicate certain individuals who show behavioral avoidance to trapping or baiting1.
Trapping
- Traps can be lethal or non-lethal, however lethal traps are only currently legal in Australia. When non-lethal traps are used, humans must routinely check the traps to ensure no cat is left in a trap for an inappropriate duration. This is time and resource consuming1.
- Traps should also be checked daily to release any other species who may have ventured into the trap5.
- Most agencies who use lethal controls set up traps and then shoot the cat once it has been trapped. Sedating and euthanizing with an overdose of barbiturates while in the field is time consuming and sometimes impossible to administer to an aggravated, scared cat trapped in a cage1.
- Similar to just shooting, trapping and then shooting is most successful in small scale events to control small populations of feral cats1.
Regardless of your stance, culling one species to protect another seems like an odd way to prioritize conservation6
- Fisher, P., Algar, D., Murphy, E., Johnston, M., & Eason, C. (2015). How does cat behaviour influence the development and implementation of monitoring techniques and lethal control methods for feral cats? Applied Animal Behaviour Science, 173, 88 - 96.
- Doherty, T.S., & Ritchie, E.G. 2016. Stop jumping the gun: A call for evidence-based invasive predator management. Conservation Letters, 15 - 22.
- Buckmaster, T., Dickman, C.R., & Johnston, M.J. (2014). Assessing risks to non-target species
during poison baiting programs for feral cats. PLoS ONE, 9(9). - Denny, E.A., & Dickman, C.R. (2010). Review of cat ecology and management strategies in Australia. Australia: Invasive Animals Cooperative Research Centre.
- Meek, P.D., Jenkins, D.J., Morris, B., Ardler, A.J., & Hawksby, R.J. 1995. Use of two humane leg-hold traps for catching pest species. Wildlife Research, 22(6), 733 - 739.
- Doherty, T.S., & Ritchie, E.G. 2016. Stop jumping the gun: A call for evidence-based invasive predator management. Conservation Letters, 15 - 22.